DNA, Genes and Protein Synthesis Flashcards
What is DNA?
DNA holds genetic information
What is RNA?
RNA transfers genetic information from DNA to the ribosomes
What are ribosomes formed from?
RNA and proteins
What is a nucleotide?
DNA and RNA are polymers of nucleotides. Each nucleotide is formed from a pentose, nitrogen containing organic base and a phosphate group.
Describe the components of a DNA nucleotide
Deoxyribose, a phosphate group and one of the organic bases adenine, cytosine, guanine or thymine.
Describe the components of an RNA nucleotide
Ribose, a phosphate group and one of the organic bases adenine, cytosine, guanine or uracil.
What bond joins two nucleotides together?
Phosphodiester bond
What is the difference between the polynucleotide chains of DNA and RNA?
A DNA molecule is a double helix with two polynucleotide chains held together by hydrogen bonds between specific complementary base pairs. An RNA molecule is a relatively short polynucleotide chain.
What does semi-conservative replication of DNA ensure
Genetic continuity between generations of cells
What does the process of semi-conservative replication involve?
1) DNA helicase causes strands to separate by breaking hydrogen bonds between them.
2) Both strands act as templates.
3) Free nucleotides attach via complementary base pairing.
4) Hydrogen bonds reform.
5) DNA polymerase joins nucleotides to the new strands by forming phosphodiester bonds
6) New DNA molecules contain one old and one new strand
How is DNA found in prokaryotic cells?
DNA molecules are short, circular and not associated with proteins.
How is DNA found in eukaryotic cells?
In the nucleus of eukaryotic cells, DNA molecules are very long, linear and associated with proteins called histones. Together a DNA molecule and its associated proteins form a chromosome.
Which organelles in eukaryotic cells also contain DNA?
Mitochondria and chloroplasts
What is a gene?
A base sequence of DNA that codes for the amino acid sequence of a polypeptide and a functional RNA (including rRNA and tRNA)
What is a locus?
A gene occupies a fixed position, called a locus, on a particular DNA molecule
What is a triplet?
A sequence of three DNA bases that code for a specific amino acid
What is the genetic code described as being?
Universal, non-overlapping and degenerate
What is an exon?
Section of base sequence that code for polypeptides
What is an intron?
A non-coding multiple repeat of base sequences between genes
What is a genome?
The complete set of genes in a cell
What is a proteome?
The full range of proteins that a cell is able to produce
What is a transcription?
Transcription is the production of mRNA from DNA. RNA polymerase joins mRNA nucleotides together. In prokaryotes transcription results directly in the production of mRNA from DNA. In eukaryotes, transcription results in the production of pre-mRNA which is then spliced to form mRNA.
What is translation?
Translation is the production of polypeptides from the sequence of codons carried by mRNA.
